In video amplifiers and the like, hum produced by 60 cycle and other interfering signals is a serious problem. This is especially true in applications where cables are used to convey signals from a distant source. In prior art circuits common mode rejection can only be accomplished through the use of differential amplifiers through the application of the hum or other objectionable signal to both inputs thereof simultaneously and in phase. Since the use of differential amplifiers requires substantial engineering redesign and, in many cases, substantial additional circuitry, it is desirable to devise circuitry which will provide common mode rejection without requiring the redesign of existing circuitry.